The present invention relates to the field of research for new cocatalyst compositions especially for use in Ziegler-Natta addition polymerization processes. More particularly, this invention is directed toward an apparatus and method of performing heterogeneous Ziegler-Natta catalyzed polymerization of olefins and related techniques for rapidly creating and testing libraries of cocatalyst compositions prepared by combinatorial techniques.
Combinatorial (also known as high throughput or parallel) chemistry and materials science techniques have been used to rapidly screen large numbers of compounds for use in biological, organic, inorganic, and organometallic synthesis and research. Combinatorial materials science generally refers to the methods for creating a collection of chemically diverse compounds or materials and to methods for rapidly testing or screening this library of compounds or materials for desirable performance characteristics and properties. Areas for application of such combinatorial methods have included the discovery of compounds for use as biologically active materials as well as high-temperature superconductors, magnetoresistive materials, luminescent compounds, and catalysts. Examples include U.S. Pat. Nos. 5,712,171, 5,776,359, 5,985,356, 6,004,617, 6,045,671, 6,326,090, 6,346,290, 6,627,571 and WO 00/40331.
In addition to the foregoing patent references, numerous academic papers have also disclosed combinatorial techniques, including: Senkan, Nature, vol. 394, pp. 350-353 (Jul. 23, 1998); Burgess et al., Angew. Chem. Int. Ed. Eng., 1996, 35, No. 2, pp. 220-222; Maier et al., Angew. Chem. Int. Ed. Eng., 1998, 37, No. 19, pp. 2644-2647; Reetz et al., Angew. Chem. Int. Ed. Eng., 1998, 37, No. 19, pp. 2647-2650; Angew. Chem. Int. Ed. Eng., 1998, 37, No. 17, pp. 2333-2336; Morken et al., Science, vol. 280, pp. 267-270 (Apr. 10, 1998); and Gilbertson et al., Tetrahedron Letters, vol. 37, no. 36, pp. 6475-6478 (1996).
Although the foregoing and other references have advanced the art of combinatorial materials testing, still further improvements and advances in the field of Ziegler-Natta catalyst development are desired. In particular, rapid techniques of screening candidate materials that are useful as cocatalyst compositions are desired.
Generally, Ziegler-Natta catalyst compositions comprise a Group 2 metal containing procatalyst composition, especially a MgCl2 supported transition metal complex, and a cocatalyst or activator. Suitable activators generally are trihydrocarbylaluminum compounds, especially trialkyl aluminum compounds such as triethylaluminum.
In WO 00/40331 a combinatorial apparatus and method for evaluating homogeneous and supported homogeneous coordination polymerization catalysts including olefin polymerization catalysts employing a metal compound formed from a metal of Groups 3-15 of the Periodic Table of the Elements and one or more ligands is disclosed.
In U. S. Pat. No. 6,627,571, a method for screening heterogeneous catalysts comprising applying a suspension of a catalyst carrier to multiple regions of a substrate and removing liquid there from to form an array of porous catalyst carriers, impregnating the array with a catalytically active component or precursor thereof and analyzing for activity was disclosed.
Ziegler-Natta catalysts can be produced by numerous techniques including physical blending of solid mixtures of magnesium halides with titanium halides or the in situ formation of precipitated halogenated solids from liquid mixtures. Solid phase forming techniques involve the use of ball-mills or other suitable grinding and comminuting equipment and are not adaptable to combinatorial research approaches. Precipitation techniques use repeated halogenations with various halogenating agents, preferably TiCl4 to prepare suitable procatalyst compositions. Other aspects of Ziegler-Natta catalysis present significant challenges to the use of combinatorial approaches in automation and reactor design, particularly due to the small size of the reaction vessels employed and the need to handle a plurality of samples. Consequently, the application of combinatorial methods to Ziegler-Natta process research has not been adequately explored.
In Adv. Synth. Catal., 2003, 345, 1299-1304, the use of donor stabilized aluminum alkyls as activators for the polymerization of propene is disclosed. In Organometallics 2003, 22, 1391-1401 modified alkyl aluminum compounds are disclosed for use as Ziegler-Natta catalyst activators. U.S. Pat. No. 5,468,707 disclosed similarly modified alkylaluminum complexes with 1 or more coordination groups. GB-A-799823 disclosed the use of organoaluminum cocatalysts including halogen, alkoxy aryloxy, amido, mercaptal, thiophenoxy, carboxy, or sulfonic acid ligands. DE 2,212,088 disclosed Ziegler-Natta catalyst compositions comprising an alkylaluminum; and alkoxyaluminum or aryloxyaluminum compounds. U.S. Pat. No. 4,377,720 disclosed using a zirconium containing Ziegler-Natta catalyst in combination with an aluminum cocatalyst including dialkylaluminum alkoxides or aryloxides and dialkylaluminum disubstituted amides. EP-A-1,132,409 disclosed Ziegler-Natta catalyst compositions employing specific alkylaluminum complexes.
It would be desirable if combinatorial research techniques could be applied to heterogeneous catalysts, especially to Ziegler-Natta catalyst compositions, comprising at least one transition metal compound, optionally supported on an inert solid material, an activator or cocatalyst, and optionally one or more polymerization modifier compounds. In particular, what is needed is a combinatorial method and apparatus for the rapid and reliable discovery and development of catalyst compositions that is particularly adapted to use in addition polymerization research, especially research related to the addition polymerization of olefin monomers to form high molecular weight polymers using Ziegler-Natta catalysts.